The present invention relates to inking systems for printing presses, and more particularly to various adjustable phasing systems for ink valves and ink pumps in series and which adjust the ink flow separately to each column of printing coming from a press. According to various embodiments of the invention, the ink may flow from 0% to 100% of a selected maximum for each column across the web.
The manner in which the ink flow is adjustably phased comprises an ink input, a phasing unit or rotary valve for the input, an injector pump unit in series with the phasing unit, and an ink output line which delivers the ink to the roller and then to the paper. One advantage of this system is that no return is made of ink which is not used; some systems pump a certain amount of ink, and this amount is divided into one portion that flows to the paper while the remainder of the ink is returned to the reservoir. Another system of the invention uses a single rotary piston with two flats, spaced axially along its length and an adjustable barrel plus appropriate passages in the barrel housing. This system uses an open yoke to allow the piston to have an intermittent motion to avoid creating a vacuum in the piston.
Known inking systems include piezoelectrically driven ink flow valves which open and close to a degree which is dependent on the need for ink at that time. Owing to the problem of variable flow rate through the valves, these systems require delicate timing, have significant expense and complexity, and have other problems as well.
In view of these and other shortcomings of the prior art, it is an object of the present invention to provide several improved, adjustable ink flow control systems and methods.
Another object is to provide a plurality of so-called phased injectors for the ink used in a modern offset press, with the injectors being either of the single-piston type, or the two-piston type.
A further object is to provide a rotary valve in series with a positive displacement pump for each column of print provided in an offset printing press, whether the pumps are a single member with two flats or reliefs or are two members each with a single flat or relief.
Another object is to provide systems in which the ink used flows from the valves to the pumping units or injectors to the press rollers, all without being returned to the ink reservoir.
A still further object is to provide, for each column of print, different methods of controlling ink flow using phase control between a rotary valve or barrel assembly and using a positive displacement pump in series with each other.
A further object is to provide methods and apparatus having easily adjustable controls for adjusting the effective phase angle between the rotary valve and the positive displacement pumps in a press inking system, whereby the exact amount of ink desired may be delivered to each of the various columns to be printed by the press.
A still further object is to provide a system without a return circuit for ink which is not desired to be used.
A further object is to provide a system of inking wherein the flow rate in view of the viscosity of the ink can be adjusted for, and in which ink viscosity is ultimately immaterial as far as the correct or desired amount of ink flow is concerned.
Another object, in one embodiment, is to take advantage of a rotary valve having a rotary-valve core and a sleeve with intake and outlet ports in series with a positive displacement pump using a reciprocable and rotatable piston and using one such valve and one pump in series for every column of printed matter in the press.
Another object of the invention is to provide three different versions of somewhat similar apparatus and which operate in similar but not identical ways, and in which each apparatus ultimately accomplishes a related novel result.
A still further object is to provide one embodiment wherein the phase control is accomplished by rotating the valve core in the rotary valve and holding the sleeve in a fixed position.
A further object is to provide another embodiment wherein phase control is achieved by means of rotating the sleeves rather than the cores of the rotary valves relative to each other.
Another object is to provide a phase control unit wherein one sleeve is inclined relative to its drive input, thereby providing the eccentric motion necessary for piston rotating and reciprocating motion.
Another object is to provide an ink supply system wherein the rotary valve and the pumping unit comprises two flats or notches in a single piston rather than two flats or notches in two separate pistons.
A still further object is to provide an embodiment of a rotary mechanism which uses an open slot yoke rather than a bearing in a yoke for rotating the piston and allowing slack in the piston movement under certain conditions.
Yet another object is to provide a barrel and a having a body with appropriate passages for ink demanded by the rotary valves or pistons.
These and other objects and advantages and the manner of their attainment will become more clearly apparent when reference is made to the following detailed description of the invention set forth by way of example and to the accompanying drawings wherein like reference numbers indicate corresponding parts throughout.